It is well-known in the key art that certain types of keys are coded in a predetermined manner. That is, keys of the type having a plurality of spaced notches of varying depth and spacing therebetween are coded by the key manufacturer to predetermined coded depths and spacing. This information is generally available to those in the key duplication trade. There have been a number of key cutting apparatus that use this predetermined code information to fashion duplicate keys from key blanks without the need of an existing key as a guide.
Examples of a key decoding apparatus by which the code of a given key can be decoded and a key duplicating apparatus by which such keys can be duplicated are disclosed in U.S. Pat. Nos. 4,012,991; 4,090,303; and 4,117,763. As more fully discussed in the '991 and '303 patent disclosures, key decoding apparatus are presently known wherein a key may have its code determined by measuring the depth of cut in association with index cards having notch spacings preindexed thereon for the spacing code of the manufacturer of the key being decoded. Once the key notch spacing and depth information is ascertained for a given key, the key can then be duplicated by the apparatus of the aforementioned patent disclosures as disclosed in the '763 patent by way of example.
In accordance with the method and apparatus of the '763 patent, once the code for depth and spacing of a given manufacturer's key has been determined, either by using the decoding apparatus discussed or having an index card with the manufacturer's code already applied thereon, the index card may be inserted into a windowed slot on the key grinding machine. The key is moveable relative the grinding wheel in predetermined manner in response to visual observation of pointers which move over the index card beneath the window so that the operator can effect the desired depth of cut and spacing of notches as provided by the code. Specifically, the blank key is located on a housing of the grinding machine in a manner related to the coded spacing of the notch to be cut by a visual observation of a first pointer sweeping across the index card. A notch is then cut at the proper location on the key to the coded depth also determined by a visual observation of a second pointer sweeping across the same index card. Sequential cuts are made in like manner. The key duplicating apparatus of these patents is fairly complex and, while providing the advantages of key duplication to a manufacturer's code provided on index cards, is relatively expensive to own by a key duplicator who might not have the volume of key duplications to justify the expense of such a sophisticated key duplicating apparatus.